Medical diagnostic ultrasound is an imaging modality that employs ultrasound waves to probe the acoustic properties of the body of a patient and produce a corresponding image. Generation of sound wave pulses and detection of returning echoes is typically accomplished by an ultrasound probe having an array of transducers. Such transducers typically include electromechanical elements capable of converting electrical energy into mechanical energy for transmission of ultrasonic waves into patient tissue and mechanical energy back into electrical energy when the reflected ultrasonic waves reach the transducers.
Multi-line transmit is a type of ultrasound imaging modality that involves each transducer element transmitting multiple ultrasonic waves during a single transmit event. Transmitting multiple ultrasonic waves during a single transmit event increases the imaging frame rate by simultaneously generating multiple lines of ultrasound data.
However, the multiple waves of the multi-line transmit may interfere with one another and result in increased pressure and intensity on the imaged tissue. The acoustic pressure and/or intensity may be quantified by a mechanical index. Mechanical index is an ultrasound safety parameter that estimates the maximum amplitude of the pressure pulse in tissue and indicates the likelihood of bioeffects such as cavitation that may cause tissue damage. Regulatory agencies such as the United States Food and Drug Administration establish ultrasound regulations that set an upper limit on mechanical index for diagnostic applications. Due to the increased number of ultrasonic waves in a multi-line transmit, interference between the waves may increase the acoustic pressure throughout the body and thus the mechanical index may be higher compared to single-line transmit ultrasound imaging. Furthermore, other acoustic parameters subject to government regulations such as spatial-peak time-averaged intensity, spatial-peak pulse-averaged intensity, total output power, and thermal index may be higher compared to single-line transmit ultrasound imaging. The inventors have recognized the above issues with multi-line transmit methods.